Orthodontic adhesives and methods of using same

ABSTRACT

An orthodontic adhesive includes components capable of allowing easy debonding of an orthodontic device from a patient&#39;s tooth. The adhesive includes an engineered marine mussel protein. The adhesive may include at least one photocleavable moiety. The adhesive is applied in one or more individual layers. One of the components of the adhesive is capable of binding to a tooth and the other component may be capable of binding to an orthodontic device. A method of adhering an orthodontic device to a tooth includes applying a layer of an orthodontic adhesive to either the tooth or the orthodontic device or the tooth and the orthodontic device and affixing the orthodontic device to the tooth with the orthodontic adhesive situated between the tooth and the orthodontic device. The engineered marine mussel protein includes one or more catechol moieties or one or more derivatives of a catechol moiety.

FIELD

The present invention is generally related to the field of orthodonticadhesives, adhesive systems, and methods of using those adhesives.

BACKGROUND

Current orthodontic treatment with orthodontic brackets or other devicesthat may be attached to the patient's teeth may require the enamel to beprepared prior to attachment of the device to the tooth. Preparation ofthe tooth surface may be through a series of steps including cleaning,acid etching, and sealing, with intermediate rinse and dry steps, beforethe clinician may apply an adhesive. For example, to bond a bracket totooth enamel, each tooth is first cleaned with a slurry of abrasive,such as pumice, to remove pellicle from the enamel. Then, after rinsingand drying the cleaned surface, a phosphoric acid etchant is carefullyplaced on the surface locations of the tooth to which the cliniciandesires to attach the orthodontic device. The acid etching stepdemineralizes the enamel surface and removes a layer of approximately 30μm or so of hydroxyapatite from the enamel rods. After between 30 and 90seconds of etch time, the etchant is rinsed away with a water spray anda high flow evacuator. In this way, etching provides a porous structure.

Following the drying step after etching, a sealant (e.g., Ortho Solo™sealant) is applied to the etched surface. The sealant may penetrate theporous, acid etched surface. Once the sealant cures, a mechanicalinterlock is created between the tooth and the sealant. An adhesive(e.g., Enlight) and the bracket may be pressed onto the sealed surfacewith the adhesive between the bracket and the sealant. The adhesive maybe a composite resin paste adhesive that includes a mixture ofmethacrylate monomers, a photo-initiator, and a glass/hydroxyapatitepowder. Once the adhesive cures, it secures the bracket to the sealant.This bonding arrangement results in a sandwich-like construction withthe sealant and the adhesive sandwiched between the tooth surface andthe orthodontic bracket. This procedure and bonding arrangement is thenrepeated for each tooth that will receive an orthodontic device and so,in the case of orthodontic brackets and molar tube, this may involve 28teeth per patient.

The current preparation process has many drawbacks. From the perspectiveof the clinician, it is a manually time-intensive process. It is notsurprising that office chair time during the entire bonding procedure islengthy. Overall, bonding orthodontic brackets to teeth is costly. Fromthe patient's perspective, the process is uncomfortable and enamelremoval is often irreversible due to the difficulty of remineralizingdental hard tissues. Thus, the tooth surface may be permanentlycompromised by acid etching. Certain patients may have an allergicreaction to the etchant. Liquid etchant may flow to the gingiva where itmay irritate the soft tissue. Gel etchant, despite allowing more preciseplacement, requires skillful application and is more difficult toremove. In either application, when the etchant must be rinsed away,care must be taken not to splash or wash the etchant in a manner thatmay harm the patient or clinician, but the rinsing must be thorough sothat the etching reaction is terminated and there is no residual acid ormineral debris that hinders the mechanical interlock between the toothand the device.

During treatment, the decalcification of the enamel surface adjacent tofixed orthodontic appliances is prevalent. Decalcification is manifestedas a white spot lesion (WSL). If left untreated, WSL may progress toproduce carious cavitations, and may also present aesthetic problems.Thus, the prevention, diagnosis, and treatment of WSLs is crucial tominimize tooth decay as well as tooth discoloration that couldcompromise the aesthetics of the patient's smile. However, the problemsand costs don't end with bonding.

After orthodontic treatment is complete, the clinician must remove theorthodontic bracket from each tooth. This debonding process requires theclinician to break the bond formed during the bonding process.Mechanically fracturing the bond may require significant skill on thepart of the clinician if the patient is to avoid pain. Even withorthodontic brackets that include design features for easier debonding,considerable adhesive/sealant residue may be left on the tooth surfaceafter removal of the bracket. This residue must be mechanically removedwith a dental bur, which is an extremely uncomfortable process for thepatient and is tedious for the clinician.

Therefore, a need exists for orthodontic adhesives, adhesive systems,and methods of using those adhesives and systems, that do not requirethe complex pre-attachment treatment described above and that reduceissues associated with debonding orthodontic devices from teeth.

SUMMARY OF THE INVENTION

The present invention overcomes the foregoing and other shortcomings anddrawbacks of orthodontic adhesives heretofore known. While the inventionwill be described in connection with certain embodiments, it will beunderstood that the invention is not limited to these embodiments. Onthe contrary, the invention includes all alternatives, modifications andequivalents as may be included within the spirit and scope of thepresent invention.

In one aspect, an orthodontic adhesive comprises an engineered marinemussel protein. The engineered marine mussel protein includes at leastone catechol moiety or catechol -like moiety.

In one embodiment, the adhesive further comprises a nitrocatecholderivative. In one embodiment, the nitrocatechol derivative isnitrodopamine, and in one embodiment, the nitrocatechol derivative isnitronorepinephrine. In one embodiment, the nitrocatechol derivative isnitroepinephrine.

In one embodiment, the engineered marine mussel protein includescatechol-methacrylate.

In one embodiment, the orthodontic adhesive includes a photocleavablebis-methacrylate.

In another aspect of the invention, a method of adhering an orthodonticdevice to a tooth comprises applying a layer of an orthodontic adhesiveto the tooth and/or the orthodontic device. The orthodontic adhesivecomprises an engineered marine mussel protein. The method furtherincludes affixing the orthodontic device to the tooth with theorthodontic adhesive situated between the tooth and the orthodonticdevice.

In one embodiment, the engineered marine mussel protein includes acatechol moiety or one or more derivatives of a catechol moiety andapplying the layer includes the catechol moiety or one or morederivatives of the catechol moiety to the tooth.

In one embodiment, the catechol moiety includes catechol-methacrylate.

In one embodiment, the method further comprises applying an acrylatemoiety and/or a methacrylate moiety onto the layer. In one embodiment,the moiety is bis-methacrylate.

In another aspect of the invention, an attachment for use with analigner during orthodontic treatment comprises an engineered marinemussel protein.

In another aspect of the invention, a kit comprises an orthodonticdevice and an engineered marine mussel protein.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute apart of this specification, illustrate embodiments of the invention and,together with a detailed description given below, serve to explain theprinciples of the invention.

FIG. 1 shows a set of orthodontic brackets with individual bracketsattached to the teeth of a patient.

FIG. 2 is a cross-sectional view taken along section line 2-2 of FIG. 1.

FIG. 3 is an enlarged view of an encircled area 3 of FIG. 2 according toone embodiment of the invention.

FIG. 4 is an enlarged view of an encircled area 3 of FIG. 2 according toone embodiment of the invention.

FIG. 5 is an enlarged view of the encircled area 3 of FIG. 2 accordingto one embodiment of the invention.

FIG. 6 is an enlarged view of the encircled area 3 of FIG. 2 accordingto one embodiment of the invention.

FIG. 7A depicts exemplary wet adhesive groups according to oneembodiment of the invention.

FIG. 7B depicts an enlarged schematic representation of the encircledarea 3 of FIG. 2 according to one embodiment of the invention.

FIG. 7C depicts exemplary monomers including polymerizable groupsaccording to one embodiment of the invention.

FIG. 8A depicts photocleavage of an exemplary monomer according to oneembodiment of the invention.

FIG. 8B depicts cross-linking and photocleavage of an exemplary monomeraccording to one embodiment of the invention.

FIG. 9 is a perspective view of one embodiment of the invention withattachments of one embodiment of the invention attached to the teeth ofa patient to facilitate orthodontic treatment with an aligner.

FIG. 10 is a cross section of the aligner and teeth shown in FIG. 9taken through one of the attachments.

DETAILED DESCRIPTION

In this Detailed Description, all references to the Periodic Table ofthe Elements refer to the Periodic Table of the Elements, published andcopyrighted by CRC Press, Inc., 2001. Also, any reference to a Group orGroups shall be to the Group or Groups as reflected in this PeriodicTable of the Elements using the IUPAC system for numbering groups. Asused herein, the term “(poly)” means optionally more than one, or statedalternatively, one or more.

To address these and other issues, in one embodiment, a clinician mayutilize an orthodontic adhesive system 10 to adhere an orthodonticdevice to a patient's tooth. As described in detail below, theorthodontic adhesive system 10 includes an engineered protein. By way ofexample only, as shown in FIG. 1, an orthodontic bracket 12 may be usedin an orthodontic procedure. One orthodontic bracket 12 may be affixedto each of a plurality of teeth 14 with the orthodontic adhesive system10. The orthodontic bracket 12 defines a substantially transverselydisposed archwire slot 16, which receives an archwire 20. Theorthodontic bracket 12 may be adhesively secured to an exterior facingsurface 22 with the orthodontic adhesive system 10. Although not shownin FIG. 1, the orthodontic adhesive system 10 may be between each of theorthodontic brackets 12 and the corresponding tooth 14. While brackets12 are shown and described herein, embodiments of the present inventionmay be utilized to bond other orthodontic appliances to the patient'steeth. For example, the orthodontic adhesive system 10 may be utilizedto bond a lingual retainer and bite turbos, to name a few, to thepatient's teeth.

With reference to FIGS. 2-6, the orthodontic adhesive system 10 mayinclude a single layer 18 of one or more components as is shown in FIG.6 or a plurality of layers 24 of individual, separately-appliedcomponents, as is shown in FIGS. 3-5. While the plurality of layers 24appear to be illustrated in equal parts in FIGS. 3-5, this is notnecessary to the invention. In accordance with the present invention,the plurality of layers 24 of individual, separately-applied componentsmay be of differing dimensions and thicknesses in relation to eachother. The layers 18, 24 include one or more components that areconfigured to bond to one of the tooth surface 22 or an orthodonticappliance 12 or form a bond between other components in a sandwich-likecomposite construction. When attached to respective teeth 14 with theorthodontic adhesive system 10, the brackets 12 and the archwire 20collectively provide orthodontic treatment.

According to the embodiments of the invention, the orthodontic adhesivesystem 10 may eliminate one or more of the tooth preparation stepsdescribed above. For example, the orthodontic adhesive system 10 may notrequire one or more of the cleaning and acid etching steps, describedabove, though the system 10 secures the orthodontic bracket 12 to acorresponding tooth 14. Furthermore, the orthodontic adhesive system 10may improve the ease with which the orthodontic bracket 12 may beintentionally removed from the tooth 14. Thus, orthodontic adhesivesystems 10 according to embodiments of the invention may not requiresignificant application of mechanical force to debond the bracket 12from the tooth 14, and so patients will not experience the discomfortduring removal.

Following removal of the orthodontic bracket 12, there will be minimal,if any, adhesive residue on the tooth 14. Embodiments of the inventionwill therefore also eliminate or minimalize post-removal cleaning of theteeth 14. As another benefit to the patient, the orthodontic adhesivesystem 10 will eliminate or minimalize demineralization issues createdby acid etching during preparation of the tooth surface. The orthodonticadhesive system 10 according to embodiments of the invention may haveself-healing properties so that the orthodontic adhesive system 10resists aging and long-term degradation. As another advantage to boththe patient and clinician, the system 10 may allow reversible bondingand debonding of the device 12 to the tooth 14. That is, a bondingnetwork of the orthodontic adhesive system 10 may be selectivelyactivated to bond and deactivated to debond with the surface of thetooth 14 or from the orthodontic device 12. A clinician may then easilycorrect the orientation of a misplaced device.

A complicating factor for orthodontic adhesives is the environment towhich the adhesive is exposed. The mouth of the patient is filled withsaliva, which is an aqueous solution of electrolytes, enzymes, andcellular matter. This environment necessitates the complicated toothpreparation process and bonding process, described above, to produce amechanical bond between the tooth and the orthodontic device.

Applicants identified that the oral environment has similarities toseawater, which is a solution of water, electrolytes, and biologicalmaterial. In the ocean, mussels possess a remarkable ability to attachand detach themselves from surfaces that are submersed in seawater.Applicants have found that using an engineered marine mussel protein orsimilar protein as a component in the orthodontic adhesive system 10will provide sufficient bond strength between an orthodontic device,such as the orthodontic bracket 12, and a tooth 14. Bonding may beaccomplished in the absence of the complicated preparation and bondingprocess described above. Embodiments of the orthodontic adhesive system10 include selected engineered mussel proteins or similar components tomimic the attachment and/or detachment functionality of the mussel inthe oral environment. The engineered mussel protein is syntheticallyproduced.

Marine mussels secrete a glue-like sticky material, known as byssus,which is responsible for the strong adhesion to rocks and other surfacesin turbulent marine environment. The byssus is a bundle of thread-likematerials that spreads out in a radially outward direction. It consistsof four parts, namely, plaque, thread, stem, and root. Mussel byssus isproteinaceous. In other words, mussel byssus is a protein derived frommarine mussels. Byssal threads are attached to the root at the base ofmussel foot where a combination of 12 retractor muscles controls thetension in them. More than 25 different mussel foot proteins (mfp) havebeen identified in byssus, out of which 5 (mfp-2 to mfp-6) are unique toplaque. These 5 mfp have a high content of the usually rare modifiedamino acid 3,4-dihydroxy-L-phenylalanine (hereinafter “DOPA”) (1).

As shown in (1) above, DOPA includes a catechol moiety. When combinedwith oxidant cations from seawater under basic pH conditions, catecholoxidation of the catechol moiety of DOPA produces quinine. The quininecan form a cross-linked polymer matrix in the bonding network. Further,when bonding to rocks, the catechol moiety of DOPA may undergo chelationwith inorganic oxides found in the rock. Cohesion between molecules ofDOPA is aided by multivalent cations, such as Fe³⁺ and Ca²⁺ ions. Thesecations form metal complexes between non-oxidized catechols of DOPA andfacilitate wet adhesion of the bonding network in seawater. It has beenfound that it is the catechol functionality of DOPA that gets attachedwith external surface during the adhesion process and so at leastfacilitates the adhesion of the mussel to a variety of substrates,including wood, metal, and mineral surfaces, among others, whensubmerged in seawater. Embodiments of the orthodontic adhesive system 10include selected engineered marine mussel proteins or similar componentsso as to mimic the attachment and/or detachment functionality of themussel in the oral environment. Exemplary adhesives include thosedisclosed in U.S. Pub. Nos. 2016/0160097 and 2017/0217999 which are eachincorporated by reference herein in their entirety. The engineeredmarine mussel protein may be synthesized or be genetically engineered.

With reference to FIG. 7A, in an exemplary embodiment, the engineeredmarine mussel protein of the orthodontic adhesive system 10 includes amonomer having a catechol moiety and/or a catechol-like moiety andtherefore have similar properties to DOPA, as is shown in (1). Thecatechol moieties and/or catechol-like moieties of the orthodonticadhesive system 10 include nitrocatechol or one or more nitrocatecholderivative-containing compounds, which provide chelation,self-polymerization, and crosslinking functionality. By way of furtherexample, FIG. 7A shows an exemplary catechol-like containing compoundhaving a wet adhesive group that binds to enamel. The wet adhesive groupincludes one or more functional monomers (FIG. 7C) that crosslink withother components of the adhesive system 10. The functional monomersinclude at least one of a phosphonate and a cyclic disulfide moiety,both of which can undergo a reaction with a polymerizable group of themonomer.

With reference to FIGS. 2-6, the catechol-like moiety and the functionalmonomer of the engineered protein adhesive of the orthodontic adhesivesystem 10 may be tethered together to form at least a portion of layer18, 24 with the catechol-like moiety bonding to the tooth surface 22.This moiety may facilitate adhesion of the monomer to the tooth surface22 in the absence of prior cleaning, etching, and drying the toothsurface 22. By eliminating one or more of these preparation steps,embodiments of the invention reduce chair time. The reduction in time tobond a single bracket to a tooth may be reduced by about 80%. Forexample, conventional preparation and adhesive may require as much as 4minutes per tooth. Embodiments of the invention may reduce that to about30 seconds per tooth. A typical bonding appointment takes from 2 to 3hours of patient commitment. Embodiments of the invention greatly reducethe time needed for bonding and is advantageous for at least thatreason. For example, according to embodiments of the invention, aclinician may bond orthodontic appliances to a patient's teeth on thesame day as an initial consultation. This is not commonly practicedbecause of the long chair time requirements associated with bondingorthodontic appliances to the patient's teeth. Moreover, the reductionin bonding time, and chair time associated therewith, results in reducedcost for the clinician while increasing potential profitability byincreasing the clinician's capacity to see more patients.

In any of the exemplary systems 10 shown in FIGS. 3-6, the monomer ofthe engineered protein adhesive adheres to the tooth surface 22 andforms a base onto which the orthodontic device is ultimately attached.For example, and with reference to FIG. 3, in one embodiment, theorthodontic adhesive system 10 may include four layers that collectivelyform the composite layer 24. In that regard, the orthodontic adhesivesystem 10 may include one or more separately applied layers 26, 28, 30,and 32 that collectively bond the orthodontic bracket 12 to the tooth14. Each of the components in the layers 26, 28, 30, 32 bonds withcomponents in the other layers and/or with the tooth 14 or theorthodontic bracket 12.

In the exemplary embodiment, the layer 26 is in direct contact with thetooth surface 22. The layer 26 includes a monomer of an engineeredmussel protein that has a catechol-like moiety described above. By wayof example, the monomer of the engineered mussel protein includescatechol methacrylate. Unlike some conventional orthodontic sealants,the catechol-like moiety forms adhesion networks through hydrogenbonding and metal-ligand complexes with hydroxyapatite without one ormore of cleaning, etching, or drying preparation steps. Additionally,the catechol-like moieties may undergo Michael addition with collagen inenamel or in dentin to chemically bond the layer 26 to the tooth surface22.

Although not shown in FIG. 3, by way of example only, the layer 26 maybe on the order of about 100 nanometers thick. The layer 26 may bethicker or thinner than 100 nanometers and may depend on applicationtechnique and viscosity of the layer 26. The layer 26 may be very thinrelative to the overall thickness of the joint formed by the adhesivesystem 10 between the bracket body 12 and tooth 14. The layers 28, 30,and 32 may be separately applied on the monomer of layer 26 attached tothe tooth surface 22.

The layer 28 may be in direct contact and may chemically bond with thecatechol-like containing monomer that forms the layer 26 before or afterthat layer cures. In the embodiment shown in FIG. 3, the layer 28 mayinclude a nitrocatechol and nitrocatechol derivative-containing compound(described below) that bonds to the dried monomer that forms the layer26. In an exemplary embodiment, the layer 28 denatures when exposed to aspecific wavelength of light. Thus, at the end of treatment, theclinician can expose the system 10 to that light to denature layer 28.As a result, that layer dissolves and releases the orthodontic bracket12. The clinician then easily removes the orthodontic bracket 12.

In one embodiment, and with reference to FIG. 3, a sealant may formlayer 30. The layer 30 may be in direct contact and may chemically bondwith the nitrocatechol and nitrocatechol derivative-containing compoundthat forms the layer 28 before or after that layer cures. In theembodiment shown in FIG. 3, the layer 30 may be an acrylate-based resinsealant that bonds to the layer 28. In one embodiment, the sealantforming the layer 30 is a commercially available orthodontic sealant,such as Ortho Solo™, available from Kerr Corporation of Orange, Calif.

As shown, the layer 32 may then be directly applied on the layer 30 in aseparate application. The layer 32 chemically bonds to the layer 30 andalso mechanically bonds to the orthodontic bracket 12. By way of exampleonly, the layer 32 may include a resin, such as a methacrylic resin,which may include an acrylate and/or a methacrylate moiety thatchemically bonds with the acrylate-based resin sealant of layer 30 whenexposed to a preselected wavelength of light. When applied, the layer 32may include a photo-initiator to facilitate curing of the layer 32. Inone embodiment, the resin is a commercially available orthodonticadhesive, such as Grēngloo® or Blūgloo, each of which is commerciallyavailable from Ormco Corporation of Orange, Calif.

In the case of the layer 32, which may include the photo-initiator, theorthodontic bracket 12 may be pressed against the composite layer 26,28, 30, and 32 shown in FIG. 3. The adhesive layer 32 may then be curedby exposing it to light, such as visible blue light (e.g., wavelengthsof about 450 nm to about 475 nm). This photo-curing process cures atleast the layer 32. By way of further example, each of the layers 26,28, 30, and 32 may be cured at the same time or at different times. Thetiming of each cure depends on the preferences of the clinician. Aclinician may prefer to partially cure the layer 26 to make it tackierand then apply the remaining layers with a final cure of each of thelayers 26, 28, 30, and 32 together. When the layers 26, 28, 30, and 32are cured, the orthodontic adhesive system 10 bonds the orthodonticbracket 12 to the tooth surface 22.

In the exemplary orthodontic adhesive systems 10 shown in FIGS. 4, 5,and 6, the functionalities described above with regard to the layers 26,28, 30, and 32 may be combined in fewer than four layers. For example,the functionality of layers 28 and 30 may be combined resulting in athree-layer system (FIG. 4). By way of further example, a two-layersystem (FIG. 5) may combine the functionality of the catechol-likemoiety of layer 26 with a sealant, such as that described above in layer30, which may include a nitrocatechol and nitrocatecholderivative-containing compound. In this case, the functionality oflayers 26, 28, and 30 of FIG. 3 is present in a layer 40 of FIG. 5.Thus, with reference to FIG. 5, the layer 40 is applied to the toothsurface 22. The catechol-like moiety of the layer 40 may form adhesionnetworks through hydrogen bonding and metal-ligand complexes with theenamel at the surface 22 without one or more of cleaning, etching, ordrying.

With reference to FIG. 5, a layer 42 may be similar to the layer 32 ofFIG. 3. Specifically, the layer 42 may include a resin, such as amethacrylic resin, which may include an acrylate and/or a methacrylatemoiety that chemically bonds with a resin of layer 40. The bondingnetwork may be schematically represented by FIG. 7B, described above.

In FIG. 6, in one embodiment, the orthodontic adhesive system 10includes the single layer 18 having components which combine thefunctions of the layers 26, 28, 30, and 32 described above. By way ofexample, a catechol-like moiety of the layer 18 may form adhesionnetworks through hydrogen bonding and metal-ligand complexes with enamelwithout one or more of cleaning, etching, or drying the tooth surface22. And, the layer 18 may include a debonding compound and a resin, suchas a methacrylic resin, which may include an acrylate and/or amethacrylate moiety that chemically bonds with the acrylate-based resinsealant and ultimately a bond is formed between the orthodontic adhesivesystem 10 and the bracket 12. The figures are not drawn to scale. Thus,while layers 26, 28, 30, and 32 in FIG. 3; layers 26, 30, and 32 inFIGS. 4; 40 and 42 in FIGS. 4; and 18 in FIG. 5, are depicted as beinguniformly thick in approximately equal thicknesses, embodiments of theinvention are not limited to the relative ratios of the thicknessesshown. The thickness of each layer can vary independently of the otherlayers.

An exemplary system orthodontic adhesive system 10 is schematicallyshown FIG. 7B. In the figure, the catechol-like containing layer 26attaches to hydroxyapatite or calcium ions in the enamel or to thedentin on surface 22. The monomer of the layer 26 may bond to the toothsurface 22 and crosslink to sealant of the layer 30 (FIG. 4). Themethacrylic resin of the layer 32 crosslinks to the surface of thebracket 12. The region in which the crosslinking occurs may appear as acrosslinking polymer brush at 36.

In an exemplary embodiment and with reference to FIGS. 8A and 8B,nitrocatechol and nitrocatechol derivative-containing compounds may beattached as end groups to a biologically acceptable polymer, such asfour-arm star-poly(ethyleneglycol), also known as PEG-N_(D4). Thenitrocatechol and nitrocatechol derivative-containing compound may thenattach, for example, to the tooth surface 22 or to a separately appliedlayer of the monomer that has a catechol-like moiety (e.g., layer 26 ofFIG. 3). Similar to the catechol moiety of DOPA, discussed above,nitrocatechol and nitrocatechol derivative-containing compounds mayundergo oxidation to form cross-linked networks or undergo metalchelation between non-oxidized nitrocatechol and its derivatives, thusproducing a strong bond between two or more nitrocatechol containingcompounds. Exemplary nitrocatechol derivative-containing compoundsinclude nitrocatechol, nitrodopamine, nitronorepinephrine, andnitroepinephrine, among others. Not only do some of these compoundsmimic the adhesiveness of DOPA to wet surfaces, the catechol-likemoiety, such as nitrocatechol or one or more nitrocatecholderivative-containing compounds, may also be photocleavable.

In that regard, the photocleavable moiety may interact with certainwavelengths of light (“hv” in FIG. 8A). As shown in FIG. 8A, in oneembodiment, the monomer including the catechol-like moiety may becleaved when exposed to certain wavelengths of light, which mayfacilitate depolymerization of at least a portion of the orthodonticadhesive system 10. An exemplary photocleavable moiety includesphotocleavable bis-methacrylate. Photocleavage of the monomer may beprovided by one or more additional moieties pendant to one or more ofthe nitrocatechol and its derivative-containing compounds describedabove.

In an exemplary embodiment, and with reference to FIG. 8B, the bondbetween a leaving group X and an ethyl group pendant to thenitrocatechol moiety is capable of being cleaved with a photon of lighthaving a predetermined energy. By way of example, the photocleavablemoiety of the orthodontic adhesive system 10 may be any moiety that iscapable of being broken when exposed to light in the infrared (IR)spectrum (i.e., wavelengths of about 700 nm to about 1 mm). Therefore,exposure to, for example, IR light may depolymerize the orthodonticadhesive system 10 and so aid in the debonding of the bracket 12 fromthe tooth surface 22. It is believed that IR light is advantageousbecause it passes through both hard (e.g., tooth) and soft (e.g., lips,cheek, and tongue) tissues. The clinician may more easily expose theorthodontic adhesive system 10 to IR light to debond brackets 12 fromthe teeth 14. Alternatively, the photocleavable moiety may be brokenwhen exposed to light in the ultraviolet (UV) spectrum (i.e.,wavelengths of about 10 nm to about 400 nm). Exemplary photocleavablemoieties include those reported in Shafiq et al., “BioinspiredUnderwater Bonding and Debonding on Demand,” 51 Angew. Chem. Int. Ed.4332-35 (2012) (hereinafter “Shafiq”), which is incorporated herein byreference in its entirety.

In one embodiment, the bond between the nitrocatechol derivative moietyand the biologically acceptable polymer may be cleaved upon exposure tolight. In this way, the orthodontic adhesive system 10 may be capable ofbeing debonded via light exposure. By way of example, the layer 30 ofFIG. 4 may include a photocleavable moiety. In that regard, exposing thebond between the nitrocatechol derivative-containing compound and thebiologically acceptable polymer to IR light may weaken or break thebond. By way of example, a typical orthodontic bracket may be bonded tothe tooth and achieve a shear strength of from 10 MPa to 20 MPa. IR orUV light exposure may reduce that shear strength to 1 MPa or less. As aresult, the nitrocatechol derivative may remain attached to the surfacewhile the biologically acceptable polymer becomes detached from thenitrocatechol derivative moiety. As applied to the embodiment of FIG. 4,for example, when exposed to IR light, the layer 30 may denature, inwhich case the layer 30 may break down so that the bracket 12 and thelayer 32 may be released from the tooth 14. Following debonding, thelayer 26 may remain on the tooth surface 22. Thus, during treatment, adental bracket may be strongly adhered to the teeth of a patient whendesired, but then may also be easily removed from the teeth whentreatment is completed or when the device needs repositioning orreplacement, by exposing the adhesive to an IR light source.

Once treatment is complete, in one embodiment, debonding may includeexposing the adhesive to IR light. The orthodontic bracket(s) 12 mayfall off or only require a slight application of force for removal. Itis thought that any force application in combination with light exposurewould be substantially less than conventional forces required to debondorthodontic devices from teeth. In addition to reducing the bondingforces, debonding may minimize or eliminate the need for grinding awayresidual adhesive once the orthodontic device is removed. In cases whereconventional adhesives needed to be removed mechanically (i.e., groundoff), patient discomfort from mechanical removal is eliminated using theadhesives of the present invention. Also, emergency appointments may beminimized because the adhesives of the present invention tend to providehigher adhesion strength. For example, bond strength with embodiments ofthe invention may reach about 15 MPa or more such that accidentaldebonding may be minimized. These bond strengths may be achieved whilealso reducing the time it takes to intentionally debond the orthodonticdevice.

In one embodiment of the invention, the clinician may remove multiplebrackets 12, even an entire arch of brackets 12, simultaneously by useof the archwire 16. The clinician may expose the orthodontic adhesivesystem 10 to IR light. Once at least a portion of the orthodonticadhesive system 10 denatures, the clinician may then pull on thearchwire 16 while it is still engaged with each bracket 12 on the arch.The brackets 12 detach while still coupled to the archwire 16. In thisway, the clinician may remove each of the brackets 12 with one pull onthe archwire 16. This process may leave no residual adhesive on theteeth 14. As another advantage, this prevents unforeseen loss oringestion of the individual brackets and can significantly reduce chairtime, for example, by greater than 90%.

Furthermore, according to embodiments of the invention, thephotocleavable moiety may enable reversible adhesion of the orthodonticadhesive system 10 to the tooth surfaces 22. The bonding process of thereversible adhesiveness may even be a type of fast curing (e.g., curingmay occur during the few moments when the clinician presses theorthodontic device against the tooth with the catecholderivative-containing compound present on the tooth and the functionalmonomer present on the restorative part). The adhesion may be reversiblein the sense that it can be bonded and then debonded at least twice.This may be useful for when the orthodontic bracket 12 is initiallyimproperly positioned. The orthodontic bracket 12 may then be debonded,reoriented, and then re-bonded to the tooth surface 22. In oneembodiment, the adhesiveness of the adhesive may be activated anddeactivated during bonding and debonding, respectively. Thus, theadhesive may facilitate an on-demand bonding and on-demand debondingprocess that permits easy repositioning of the orthodontic device. Thismay be referred to as a reuseable adhesive system. Advantageously,orthodontic device placement may be perfected without concern that theadhesive polymerizes prior to proper positioning as the adhesive may beselectively bonded and debonded and then rebonded without addition ofmore adhesive. Clinically, the process of repositioning is common andtedious, thus embodiments of the adhesive described herein savesrepositioning time presents a significant shift in the standard ofpatient care.

In one embodiment of the invention, the orthodontic adhesive may be usedin a kit. The kit may include an orthodontic device, such as orthodonticbracket 12, on which the orthodontic adhesive is pre-applied. The kitmay include a bubble pack in which the brackets 12 are individuallydisposed. The clinician may remove the orthodontic brackets 12individually from the packaging in a particular order and press them tothe patient's teeth. The clinician may then cure the pre-appliedadhesive with light, such as blue light.

With reference now to FIGS. 9 and 10, in one embodiment, the orthodonticadhesive system 10 may be utilized with other orthodontic appliances,such as an aligner 60. The aligner 60 may be configured to fit over andinteract with one or more attachments 62 bonded to one or more teeth 14.Each attachment 62 may be a structure of predetermined shape of theorthodontic adhesive system 10. That is, the orthodontic adhesive system10 may be formed into a rectangular, square, circular, ellipsoidal ortriangular-shaped attachment that is bonded to the tooth surface in amanner similar to that described above respect to the orthodonticbrackets 12 (FIG. 1). The attachment 62 may be formed completely of theadhesive system 10.

The aligner 60 may be configured with a corresponding bulge 64 thatengages the attachment 62 during orthodontic treatment. Advantageously,each of the attachments 62 may be easily bonded to the tooth surfaceprior to treatment with an aligner 60 and then may be easily debonded byexposing them to a particular wavelength of light. The attachments 62may be applied to the tooth with the use of a template (not shown) thatallows the clinician to more easily locate the attachment 62 on thepatient's tooth. An accurately placed attachment 62 may interact withthe corresponding bulge 64 in the aligner 60.

In order to facilitate a more complete understanding of the embodimentsof the invention, the following non-limiting example is provided.

EXAMPLE 1

A primer solution of 7.5 wt. % 10-Methacryloxydecyl Dihydrogen Phosphate(MDP) that is modified to have a lower acid value (i.e., purified byremoving HCl byproduct), 0.005 wt. % Catechol-methacrylate (CMA) (usingeugenol as a backbone for the CMA), and 0.0075 wt. % butylatedhydroxytoluene (BHT) in a balance of acetone was applied with a brush toa bovine tooth that was prepared by wiping it with a tissue. No otherpreparation techniques were used to prepare the surface of the tooth.

A second solution of 10 wt. % photocleavable bis-methacrylate, 0.01 wt.% N,N-di-methyl-amino-ethyl methacrylate (DMAEMA), 0.01 wt %camphoroquinone (CQ), and 0.001 wt % BHT in a balance of acetone wasapplied with a brush to the dried primer. This forms a debonding layer.

Ortho Solo® sealant is applied to the debonding layer.

Grēngloo® adhesive is placed on an orthodontic bracket and then ispressed against the debonding layer with the adhesive in contact withthe debonding layer.

The layers were then exposed to a broad spectrum curing light for a fewseconds (about 5 seconds or so). Total preparation and bonding time wasabout 1 minute per sample.

Bond strength as measured for multiple samples was 17 MPa to 19 MPa.

Wire shear bond strength for a sample size of 30 ranged from a high of36.3 MPa to a low of 17.4 MPa. To demonstrate debonding, a first groupof 30 samples assembled as set forth above were exposed to UV light for10 seconds. Following exposure, the wire shear bond strength ranged froma high of 15.6 MPa to a low of 12.7 MPa. A second group of 30 samplesassembled as set forth above were exposed to UV light for 30 seconds.Following exposure, the wire shear bond strength ranged from a high of9.5 MPa to a low of 0.

COMPARATIVE EXAMPLES

Commercially available adhesives were used to bond the orthodonticbracket to bovine teeth for comparison with Example 1. Themanufacturers' instructions were followed for bonding of allcommercially available adhesives. A standard tooth preparation techniqueprior to bonding a bracket to each tooth included, in order: cleaningthe tooth with pumice, water rinse, air dry, and apply etching solution.

Two groups of 30 samples each were prepared with each of Orthosolo® andGrengloo® and Transbond™ XT Primer and Transbond™ XT Adhesive availablefrom 3M.

Another group of 30 samples of Self-etching Transbond™ Plus Primer(L-pop delivery) and Transbond™ XT Adhesive were also prepared.

Wire Shear Bond testing of each provided the following results incomparison with Example 1 experimental samples.

Wire Shear Bond Strength Wire Shear Bond Strength Adhesive System High(MPa) Low (MPa) Orthosolo/Grēngloo ® 21.2 14.3 Transbond XT ™ Primer26.2 13.6 and Transbond ™ XT Adhesive Transbond ™ XT Plus 13.6 9.1Primer and Transbond ™ XT Adhesive Example 1 36.3 17.4 Example 1 after10 second 15.6 12.7 UV exposure Example 1 after 30 second 9.5 0 UVexposure

While the present invention has been illustrated by a description ofvarious preferred embodiments and while these embodiments have beendescribed in some detail, it is not the intention of the inventors torestrict or in any way limit the scope of the appended claims to suchdetail. Additional advantages and modifications will readily appear tothose skilled in the art. The various features of the invention may beused alone or in any combination depending on the needs and preferencesof the user.

What is claimed is:
 1. An orthodontic adhesive comprising: an engineeredmarine mussel protein.
 2. The orthodontic adhesive of claim 1, whereinthe engineered marine mussel protein includes at least one catecholmoiety or catechol-like moiety.
 3. The orthodontic adhesive of claim 2,further comprising a nitrocatechol derivative.
 4. The orthodonticadhesive of claim 3, wherein the nitrocatechol derivative isnitrodopamine.
 5. The orthodontic adhesive of claim 3, wherein thenitrocatechol derivative is nitronorepinephrine.
 6. The orthodonticadhesive of claim 3, wherein the nitrocatechol derivative isnitroepinephrine.
 7. The orthodontic adhesive of claim 1, wherein theengineered marine mussel protein includes catechol-methacrylate.
 8. Theorthodontic adhesive of claim 1, further including a photocleavablebis-methacrylate.
 9. A method of adhering an orthodontic device to atooth comprising: applying a layer of an orthodontic adhesive to thetooth and/or the orthodontic device, the orthodontic adhesive comprisingan engineered marine mussel protein; and affixing the orthodontic deviceto the tooth with the orthodontic adhesive situated between the toothand the orthodontic device.
 10. The method of claim 9, wherein theengineered marine mussel protein includes a catechol moiety or one ormore derivatives of a catechol moiety and applying the layer includesthe catechol moiety or one or more derivatives of the catechol moiety tothe tooth.
 11. The method of claim 10, wherein the catechol moietyincludes catechol-methacrylate.
 12. The method of claim 10, furthercomprising: applying an acrylate moiety and/or a methacrylate moietyonto the layer.
 13. The method of claim 12, wherein the moiety isbis-methacrylate.
 14. An attachment for use with an aligner duringorthodontic treatment, the attachment comprising: an engineered marinemussel protein.
 15. A kit comprising: an orthodontic device; and anengineered marine mussel protein.